Here we examine the function of ATM and ATR at telomeres in Arabidopsis. Although plants lacking ATM or ATR display wild-type telomere length homeostasis, chromosome end protection is compromised in atm atr mutants. Moreover, atm tert Arabidopsis experience an abrupt, early onset of genome instability, arguing that ATM is required for protection of short telomeres. ATR, by contrast, is required...

Most normal mammalian cell lines demonstrate limited growth capacity due to the gradual accumulation of senescent cells in the culture. Senescent cells appear initially at a low incidence, but with increasing frequency as the culture accumulates more divisions. Because it has been suggested that senescence is regulated by telomere shortening in human cells, we compared the telomere lengths of t...

In Saccharomyces cerevisiae and in humans, the telomerase RNA subunit is bound by Ku, a ring-shaped protein heterodimer best known for its function in DNA repair. Ku binding to yeast telomerase RNA promotes telomere lengthening and telomerase recruitment to telomeres, but how this is achieved remains unknown. Using telomere-length analysis and chromatin immunoprecipitation, we show that Sir4 - ...

Telomere reprogramming and silencing of exogenous genes have been demonstrated in mouse and human induced pluripotent stem cells (iPS cells). Pigs have the potential to provide xenotransplant for humans, and to model and test human diseases. We investigated the telomere length and maintenance in porcine iPS cells generated and cultured under various conditions. Telomere lengths vary among diffe...

There is increasing evidence suggesting that short telomeres and subsequent genomic instability contribute to malignant transformation. Telomere shortening has been described as a mechanism to explain genetic anticipation in dyskeratosis congenita and Li-Fraumeni syndrome. Since genetic anticipation has been observed in familial breast cancer, we aimed to study telomere length in familial breas...

Telomere length and the rate of telomere shortening have been suggested as particularly useful physiological biomarkers of the processes involved in senescent decline of somatic and reproductive function. However, longitudinal data on changes in telomere length across the lifespan are difficult to obtain, particularly for long-lived animals. Quasi-longitudinal studies have been proposed as a me...

Changes in telomere length are believed to reflect changes in physiological state and life expectancy in animals. However, much remains unknown about the determinants of telomere dynamics in wild populations, and specifically the influence of conditions during highly mobile life-history stages, for example migration. We tested whether telomere dynamics were associated with migratory behaviour a...

Telomere length shortens with aging, and short telomeres have been linked to a wide variety of pathologies. Previous studies suggested a discrepancy in age-associated telomere shortening rate estimated by cross-sectional studies versus the rate measured in longitudinal studies, indicating a potential bias in cross-sectional estimates. Intergenerational changes in initial telomere length, such a...

Telomere shortening and lack of telomerase activity have been implicated in cellular senescence in human fibroblasts. Expression of the human telomerase (hTERT) gene in sheep fibroblasts reconstitutes telomerase activity and extends their lifespan. However, telomere length is not maintained in all cell lines, even though in vitro telomerase activity is restored in all of them. Cell lines expres...

Telomeres protect chromosome ends from fusing to double-stranded breaks (DSBs). Using a quantitative real-time PCR assay, we show that nonhomologous end joining between a telomere and an inducible DSB was undetectable in wild-type cells, but occurred within a few hours of DSB induction in approximately 1/2000 genomes in telomerase-deficient cells and in >1/1000 genomes in telomerase-deficient c...